<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>

  <div id="app">
    姓：<input type="text" v-model="firstName"><br>
    名：<input type="text" v-model="lastName"><br>
    <span>{{fullName}}</span><br>
    <button @click="changeName()">修改姓名</button>
  </div>
  <script src="../js/vue.js"></script>
  <script>
    const app = new Vue({
      el: '#app',
      data: {
		firstName:'张',
		lastName:'大嘴',
      },
	  methods: {
		changeName(){
			this.fullName = '张小嘴'
		}
      },
      computed: {
		fullName:{
			get() {
				return this.firstName+this.lastName
			},
			set(value) {
				this.firstName = value.slice(0,1),
				this.lastName = value.slice(1)
			}
		}
      }
    })
  </script>
</body>
</html>